[tlug] limitation on using md0 as /

[Nobuyoshi KAMEI <zic-tlug@example.com>]

Hello,

Can someone let me know if there are any limitations on using md0 as /
in Fedora 8 x86_64, especially during boot ?


I once successfully used to use md0 as / when I was using kernel
2.6.23.9-85.fc8, but recently probably after kernel 2.6.23.14-107.fc8,
it fails.


On Fedora 8 x86_64  (2.6.23.14-107.fc8),

I created /dev/md0 and want to use it as /.


Here is md0 definition:
	ARRAY /dev/md0 level=raid1 num-devices=4
	devices=/dev/sda2,/dev/sdc1,/dev/sdb15,/dev/sdd5

grub.conf entry is:
	root (hd0,1)
	kernel /vmlinuz-2.6.23.14-107.fc8 ro root=/dev/md0 rhgb
	initrd /initrd-2.6.23.14-107.fc8.img

During the boot, messages on the screen is something like (not accurate),

	No devices found for md0
	md0 stooped

	no root device

and the boot fails because mout root fails.


If I use sdc15 as root, it can start.

And sda - sdc are all SATA drives, and PATA sdd follows on kernel
2.6.23.14-107.fc8.


It used to be PATA sda comes first, and SATA sdb - sdd followed on
kernel 2.6.23.9-85.fc8.


Here are several facts.

in the grub.conf, there are lines,
	root (hd0,1)

but actually, this is the 2nd partition in the PATA drive, so after the
kernel 2.6.23.14-107.fc8 boot, it becomes sdd2.

Additionally after the boot, executing

	/sbin/mdadm -A -s --auto=yes

would not recognize the md0.

But executing

	/sbin/mdadm -Ac partition -m 0 /dev/md0

would correctly detect the md0 and it starts.


Meanwhile, md1 which consists:

	ARRAY /dev/md1 level=raid1 num-devices=3
	devices=/dev/sdc2,/dev/sdb9,/dev/sda3

can be recognized and started by executing

	/sbin/mdadm -A -s --auto=yes


I want to boot using md0 but I cannot find a way right now.


Can someone let me know the procedures for problem analysis?


regards,

zic